Irrigation Water Quality for Leafy Crops: A Perspective of Risks and Potential Solutions

Abstract

There is increasing evidence of the contribution of irrigation water in the contamination of produce leading to subsequent outbreaks of foodborne illness. This is a particular risk in the production of leafy vegetables that will be eaten raw without cooking. Retailers selling leafy vegetables are increasingly targeting zero-risk production systems and the associated requirements for irrigation water quality have become more stringent in regulations and quality assurance schemes (QAS) followed by growers. Growers can identify water sources that are contaminated with potential pathogens through a monitoring regime and only use water free of pathogens, but the low prevalence of pathogens makes the use of faecal indicators, particularly E. coli, a more practical approach. Where growers have to utilise water sources of moderate quality, they can reduce the risk of contamination of the edible portion of the crop (i.e., the leaves) by treating irrigation water before use through physical or chemical disinfection systems, or avoid contact between the leaves and irrigation water through the use of drip or furrow irrigation, or the use of hydroponic growing systems. This study gives an overview of the main problems in the production of leafy vegetables associated with irrigation water, including microbial risk and difficulties in water monitoring, compliance with evolving regulations and quality standards, and summarises the current alternatives available for growers to reduce microbial risks.

Spatiotemporal Variability in Microbial Quality of Western US Agricultural Water Supplies: A Multistate Study

“…Notwithstanding this gap in knowledge, irrigation water has long been regarded as an important vehicle for pathogens associated with foodborne illnesses (Uyttendaele et al, 2015). According to the Centers for Disease Control and Prevention, outbreaks that occurred during 2013 to 2014 from drinking water systems solely supplied by surface water accounted for nearly 80% of reported cases (Allende and Monaghan, 2015; Benedict et al, 2017; Uyttendaele et al, 2015). However, there is a paucity of research capable of linking microbial contamination in irrigation water to foodborne outbreaks in the United States (Pachepsky et al, 2016; Partyka et al, 2018).…”

Microbial quality and suitability of roof-harvested rainwater in rural villages for crop irrigation and domestic use

“…The presence of such pathogens could be transmitted to leafy green vegetables when RHRW is used for irrigation purposes. Several studies have linked irrigation water with pathogens isolated from fresh produce (Allende & Monaghan 2015;Gelting et al 2015), therefore substandard irrigation water is a contamination risk factor of fresh green leafy vegetables. The presence of human pathogens on irrigated crops due to the use of contaminated irrigation water is well described (Pachepsky et al 2011).…”

“…Reports on the role of irrigation water in the contamination of produce subsequently leading to foodborne illness outbreaks are increasing (Allende & Monaghan 2015). The transfer of any pathogen in water used for irrigation on to crops could be risky if produce is consumed fresh.…”

Dissemination of enteroviruses in the production chain of organic lettuce in Rio de Janeiro, Brazil

“…; De Oliveira Pereira et al., ; Espinosa, Arias, Sánchez‐Colón, & Mazari‐Hiriart, ; Ndiaye, Diop, & Diop, ). Elsewhere, some studies have shown that EV can be transferred onto the surface of vegetables through spray irrigation water resulting in viral contamination of the vegetables (Allende & Monaghan, ; Cheong et al., ; Pachepsky, Shelton, McLain, Patel, & Mandrell, ; Uyttendaele et al., ).…”